Surface treating appliances such as vacuum cleaners are usually provided with one or more surface treating heads, often referred to as a cleaner head. It is common for cleaner heads to be able to be manipulated between different “modes” of use. The different modes can, for example, allow for more effective cleaning by the surface treating head on different types of floor surface, such as carpeted or hard floors.
One example of the different modes that can be provided in a surface treating head is to have a set of brushes that can be raised or lowered with respect to a soleplate. In a raised position, the soleplate may be positioned lower than the brushes, and so will be in direct contact with the floor surface being cleaned. This mode is particularly beneficial when cleaning carpeted floors. This allows working edges provided on the soleplate to penetrate into the carpet and positions a suction cavity opening in close proximity to the carpet, both of which help to improve pick-up of dirt trapped within the carpet. However, on a hard floor surface, the working edges would slide along the surface of the floor with barely any effect on loosening the dust and dirt to be picked up, and would therefore act to worsen the pick-up performance. Therefore, the set of brushes can be lowered below the soleplate which act to loosen the dirt on a hard floor surface in advance of the suction cavity passing over the hard floor surface, such that dirt pick-up is improved.
Unfortunately, movable brushes within the surface treating head can give rise to a decrease in suction if air is able to pass through any gaps formed between the brushes and the body of the surface treating head. Furthermore, it is well-known that to improve suction, it is desirable to provide a good seal between the suction cavity and the floor surface being cleaned. Having brushes that move up and down can also disrupt the seal and can reduce the suction generated at the floor surface.